Plus, I doubt the payoff would make the investment worth it. Electrification over long-haul routes would save substantial money in fuel, but short-haul trucking just doesn't use enough fuel to make any financial sense for a potential change to electrification. In order to make the system work, you'd have to electrify every street in the metropolitan area, a network of probably several dozen thousand miles, if not more, in a large city like Boston. And just think: how often does a semi-truck come lumbering down your residential street? I have no idea of the per-mile figure for overhead trolley wires (it's probably significantly less than the $1-million-per-mile figure I've heard for mainline railroad electrification, since speeds and pressures are less and you don't have to worry about special constant-tension mountings, etc.), but even if a city block costs $50,000 to electrify, would it really save $50,000 in energy costs over even a ten-year span for the two or three moving trucks that might come down it in a year?
I think my current street has a no trucks sign on it.
The moving truck example, while it happens to be the thing that got me started down the path to thinking about this, is probably not the best example.
USPS, Fedex, and UPS probably all come down my street at least once a day. There's also a garbage truck once a week, a recycling truck once a week, and I presume yard waste gets collected on a third truck, but that's very roughly half the weeks of the year.
Electrifying only the main streets (instead of all of the side streets) wouldn't be feasible, either, since trucks, by their flexible nature, would eventually leave the main street and travel on a side street for their actual delivery--or they'd leave the city's road network entirely on the Interstate and head for long-haul travel. Either way, they'll need their own power at some point.
But if you think of side streets very close to main streets and supermarket deliveries, I'm not sure the side streets would necessarily need all that much wire.
Google Maps tells me that taking Davenport Street from Massachusetts Ave in Cambridge, MA to Elm Street in Somerville is 0.1 mile. There are existing trolleybus wires on Massachusetts Ave. Star Market's loading dock is on Davenport near the Elm Street end. Elm Street would gain trolleybus wires if the MBTA was handed a large pile of money to electrify all the bus routes, since the 87 bus goes past Star Market on Elm Street.
So then the question is, how cheaply could the wiring be installed for Star Market deliveries? If it did cost $1 million per mile and they needed a hundredth of a mile to get from Elm Street to their loading dock (I have no idea how you back up with that style of wiring, but let's ignore that problem for now), that's about $10,000. If you figure you're going to pay for it over 10 years in a slightly oversimplified fashion, that's $1,000 a year, or very roughly $3 / day.
That may well argue for dual mode electric / diesel trucks, since I bet covering that hundredth of a mile with a diesel engine requires a lot less than $.25 of diesel, or perhaps it even confirms the idea that local deliveries just don't use enough energy to be worth worrying about.
1) Install it on a very limited network of very heavily used shipping corridors--for example, from the port to the rail yard, which thousands of trucks move between each day and the route is limited to that single route. There is no possibility of deviating, because these trucks aren't making local deliveries--they are moving containers from ships to trains.
For that particular example, there's a huge labor savings available if you simply extend the train tracks directly to the port. Boston is pretty terrible in this regard: there are already train tracks on the opposite side of Reserved Channel from the container port. MassPort's website claims that a couple miles on a truck is a convenient way to make a rail connection. And we don't quite have double stack compatibility, either.
2) Instead of overhead trolley wires, invest in battery technology to make plug-in-hybrid trucks a reality. The payoff will be much better, since it offers much more flexibility and will be used much more widely: for example, a truck can make a delivery to, say, a furniture store and return to the loading dock to recharge while the trailer is reloaded.
I believe I've heard something about an $80,000 or so automobile that has a range of something like 200-250 miles on a charge. That's probably a two ton automobile. For a large semi truck, the weight is more like 40 tons. If you assume $50,000 of that car is the batteries, and that a vehicle 20 times heavier will have something like 1/20th the range on the same batteries, that gets you a 10 mile range.
The other issue is that batteries have a finite lifespan. 200 full charge / discharge cycles is probably not a terrible guess. So if a $50,000 ``investment'' in batteries is good for 200 charges times 10 miles each, that's 2,000 miles, and $25/mile in battery depreciation. Maybe in a truck you can use lead acid batteries instead of something like lithium ion, nicad, or nimh, which weigh more but cost less per watt hour, but when that truck probably costs less than $5/mile to buy diesel for if it has a diesel engine, justifying the batteries might be hard.
Then again, if we were discussing a $3/day, one hundredth of a mile overhead wire above, and comparing that to $.25 in battery depreciation each day to drive in and another $.25 in battery depreciation each day to drive out, maybe you need somewhat more than one delivery a day to justify the overhead wiring.
This is probably based on a high estimate of the cost of overhead wiring (since it's based on the $1 million / mile figure) and a high cost of batteries (since it's based on something more expensive per watt hour than lead acid), but if you adjust both of those down, the general conclusion seems to be that batteries probably are a good idea, contrary to what my initial impression was, though diesel fuel may still be a lot cheaper.
Don't get me wrong, Joel--I don't mean to shoot your ideas down.
A significant part of coming up with good ideas involves considering lots of options and gradually figuring out why some of them don't actually work so well. Giving others the opportunity to shoot ideas down is useful for figuring out which ideas are actually any good.
One other issue we haven't talked about is that raising and lowering trolley poles may be problematic. When the SL1/SL2/SL3 MBTA buses are running, there's at least one person whose job is to meet the buses and raise / lower the trolley poles at Silver Line Way in Boston during the mode shift. If vehicles are going to turn onto side streets that don't have trolleybus wiring, the poles are going to have to be raised and aligned correctly with the two wires somehow when they get back onto the major street. The technology I have observed the MBTA using seems to require stopping the vehicle and having someone get out to raise the poles, which is not something you want to be doing frequently in the middle of a busy street. But maybe this can be automated; in theory if everything is working right, the trolleybuses that the MBTA runs out of Harvard Square never need to have their poles raised / lowered, so there hasn't been much incentive to come up with something more automated.
